Dispensing packages for stick type medications, cosmetics, deodorants, antiperspirants and the like have been in use for many years. Many of such packages have employed elevating mechanisms designed to advance the product outwardly from a protective sleeve to a position wherein the user is able to apply the product in its intended manner. As shown in U.S. Pat. No. 2,818,167, which issued to W. E. McKinley on Dec. 31, 1957, one such mechanism can comprise a handwheel mounted for rotation on the end of the sleeve and having a threaded stem which projects through and is in threaded engagement with a threaded central aperture of a pusher or elevating member disposed within the sleeve and supporting the product. Similar types of elevating or dispensing arrangements are also shown in U.S. Pat. No. 2,573,828, which issued to C. H. Braselton on Nov. 6, 1951 and in U.S. Pat. No. 2,284,218, issued to J. K. Livingston on May 26, 1942.
In such packages, however, the projection of the threaded stem into the product causes an appearance problem with stick type products. In this connection, after the stick has been partially used a central hole (or, if the material is soft, an unattractive depression) appears in the applicating surface. Moreover, such packages which contain products with volatile components provide problems in sealing against leakage between the stem and the elevating member.
One approach to the solution of the appearance problem is to prevent the stem from extending through the elevating member. This is shown, for example, in U.S. Pat. No. 2,815,122, issued Dec. 3, 1957 to L. L. Lerner et al., wherein the threaded means to raise the elevator is located entirely underneath the elevating member. A similar structure is shown in U.S. Pat. No. 2,815,123, issued on Dec. 3, 1957 to A. Safianoff. In the Lerner et al. device the package is said to be sealed by an elongated cap which telescopes over the sleeve and frictionally engages the lower portion thereof. Since this overall seal involves at least four surfaces which have to be pressed into intimate contact to be effective, it will be readily seen that very close molding tolerances would have to be maintained, an elongated cap is essential and that the cap would have to fit tightly enough that removal would be difficult.
In the above-cited McKinley patent, the sealing problem at the lower end of the dispenser is purported to be effected in two locations, i.e. one being between the portion of lower surface of the elevator which surrounds the central aperture and an annular ridge on the stem and the other being between the periphery of the lower surface of the elevator and the periphery of the end wall of the sleeve. The seals are to be simultaneously effected by turning the handwheel so as to force the elevator downwardly into the described dual sealing arrangement. This requires a very flexible elevator, requires very close molding tolerances and prevents quick and non-critical bottom assembly of the elevator within the sleeve. The upper seal of the McKinley dispenser is achieved by means of a short cap which is threadedly engaged with the applicating end of the sleeve.
Another problem in connection with stick dispensers using screw type elevating mechanisms is that of preventing relative rotation between the elevator and the sleeve since this would result in the elevator merely rotating in position when the handwheel is turned, thus failing to advance or retract the stick. In the cited McKinley patent this was accomplished by providing ribs full length along the bore of the sleeve and mating notches on the elevator. A similar system is mentioned in U.S. Pat. No. 3,420,417, issued to J. V. Kardel on Jan. 7, 1969 with reference to a dispenser using a screw-actuated piston.
The aforementioned Lerner et al. dispenser, on the other hand, employs a elevator of polygonal cross section and a plurality of mating flats on the portion of the bore of the sleeve housing the elevator in its entirety during movement from its lowermost to uppermost positions. In the cited Livingston patent, one embodiment shows a container of polygonal cross section and a mating piston to prevent rotation. Livingston also shows the use of paper or cellophane washer having a downturned flange fitting between the piston periphery and container side walls to prevent leakage of a paste product. It is apparent, however, that such a structure cannot establish a vapor seal about the piston in a commercially feasible manner.
It is an object of the present invention to provide in a dispenser for stick types of products an arrangement of components which obviates the above described problems.
It is another object of the present invention to provide such a dispenser which can be adapted for use with either "tall" caps (i.e. enveloping the sleeve and forming an overall package seal by engagement with the lower portion of the package) or, optionally, with "short" caps (i.e. sealing only the applicating end of the sleeve).
It is a further object of the present invention to provide such a dispenser which is economical to produce, visually attractive, capable of high speed assembly and loading and which will protect its contents from degradation during long term storage.